plants dissolving?

[angyles]

I set up my 50g christmas day and it looked great. All the plants were healthy. For substrate I used 1 layer of gravel, a layer thin layer of potting soil/kittly litter combo, another layer of gravel and then sand. I've been fertilizing and haven't done a water change until this morning. Now, 1 week later, a lot of my plants seem to be dissolving. Some leaves are turning brown, but most are just turning soggy and thin. I've never seen anything like it.

What would cause this? What would make a plant stay green, but just start dissolving into mush? Is it my substrate? Is it over fertilization? I have 120watts of light on it, all generic full spectrum grow light tubes from lowes.

I don't wanna have to start over

 

[fishhead]

What sort of plants do you have in there? Cryptocorynes often will 'melt' when you transplant them or when tank parameters change.

What sort of ferts are you using?

Do you know what your Nitrate levels are/have been? Any info on tank parameters would probably be helpful.

Are you using CO2?

 

[RTR]

Ditto for new sword plants that are normally grown emerse for sale, then lose those leaves when sumberged to put out new submerse foliage.